Investment casting, in which molten metal is poured into hot molds, allows for the production of aluminum parts with extremely thin sections, knife edges and sharp detail. This article describes the various steps in the investment casting process, including patternmaking and dimensioning, the design and manufacture of shell molds, melting and casting methods, and postcasting operations such as knockout, core removal, and cleaning. It also addresses a wide range of design considerations, discusses casting defects, and provides several design examples.

This article discusses slurry molding that encompasses two distinct processes: plaster molding and ceramic molding. Plaster mold casting is a specialized casting process used to produce nonferrous castings that have greater dimensional accuracy, smoother surfaces, and more finely reproduced detail. The article describes three generally recognized plaster mold processes, namely, conventional plaster mold casting, the Antioch process, and the foamed plaster process. Ceramic molding techniques are based on processes that employ permanent patterns and fine-grained zircon and calcined, high-alumina mullite slurries for molding. The Shaw process and the proprietary Unicast processes are also discussed.

Depending on the size and application, castings manufactured with the expendable mold process and with expendable patterns increase the tolerance from 1.5 to 3.5 times that of the permanent pattern methods. This article reviews the two major expendable pattern methods, such as lost foam and investment casting. It discusses the Replicast casting process that involves patternmaking with polystyrene and a ceramic shell mold. The article contains a table that summarizes the differences in the steps of casting a part between the permanent pattern and expendable pattern methods.

This article discusses the sequence of operations for producing a foam pattern for casting. It provides information on expandable polystyrene, the most preferred material for manufacturing lost foam patterns. The article then describes the major functions of pattern molding and assembly. The types and application methods of various lost foam coatings are explained. The article also describes the investment of the foam pattern in a sand system. It concludes with a discussion on the advantages of lost foam casting and information on the formation and control of folds.

Casting can be done with either expendable molds for one-time use or permanent molds for reuse many times. This article lists the various methods used to fabricate expendable molds from permanent patterns. The methods include molding of sand with clay, inorganic binders, or organic resins; shell molding of sand with a thin resin-bonded shell; no-bond vacuum molding of sand; plaster-mold casting; ceramic-mold casting; rammed graphite molding; and magnetic (no-bond) molding of ferrous shot. The article tabulates a general comparison of casting methods and discusses the basic requirements of foundry molds.

This article reviews the pattern materials used in investment casting, which can be loosely grouped into waxes and plastics. The patternmaking process, pattern tooling, and pattern and cluster assembly are described. The article also describes the manufacture of ceramic shell molds and cores, detailing the binders and other materials used, as well as the formulation and control of slurries. Methods for pattern removal, mold firing, melting, casting, postcasting treatment, and inspection are explained. After presenting design recommendations for investment castings, the article concludes with information on applications and special versions of the investment casting process.

This article reviews the basic types of mold aggregates and bonding methods for expendable molds and coremaking. It provides an overview of mold media and the basic types of sands and their properties. The most significant clays used in green sand operations, such as bentonites, are discussed. The article describes the methods of sand bonding with inorganic compounds. It provides a description of resin-bonded sand systems: no-bake binder systems, heat-cured binder systems, and cold box binder systems. The article concludes with a discussion on the media used for expendable molds, namely, ceramic shells and rammed graphite, for casting reactive metals such as titanium or zirconium.

This article discusses the types of patterns used for a specific application such as loose patterns, match plate patterns, cope and drag patterns, and special patterns. It describes the principles of the patternmaking techniques used to make expendable molds and for metal casting processes such as die casting and permanent mold casting. The article reviews the pattern features and mold production considerations used in the pattern design, namely, parting line considerations, addition of gates and risers, core prints, and locating points. It examines the pattern allowances for ensuring a dimensionally correct final pattern. A variety of materials and advanced composite materials used in the manufacture of patterns are discussed. The article evaluates the factors influencing the selection of type of patterns for specific castings.